OVERVIEW

Infection Channel:

Propagates via removable drives, Downloaded from the Internet, Dropped by other malware

This worm arrives by connecting affected removable drives to a system. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

TECHNICAL DETAILS

File Size:

290,816 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Oct 2012

Payload:

Compromises system security

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This worm drops the following copies of itself into the affected system:

%User Profile%\{random}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

Press F8 after Windows starts up. If the Windows Advanced Options menu does not appear, try restarting again and pressing F8 several times afterward.

On the Windows Advanced Option menu, use the arrow keys to select Safe Mode then press Enter.

• For Windows Vista and Windows 7 users

Restart your computer.

Press F8 after the Power-On Self Test (POST) routine is done. If the Advanced Boot Options menu does not appear, try restarting and then pressing F8 several times after the POST screen is displayed.

On the Advanced Boot Options menu, use the arrow keys to select the Safe Mode option, and then press Enter.

Step 3

Delete the registry entry with an unknown data value

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Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

{random} = "%User Profile%\{random}.exe /{random letter}"

To delete the registry entry this malware created:

Open Registry Editor. To do this, click Start>Run, type regedit in the text box provided, then press Enter.

In the left panel of the Registry Editor window, double-click the following: HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Run

In the right panel, locate and delete the entry or entries whose data value is the malware path and file name of the file(s) detected earlier.

Close Registry Editor.

Step 4

Delete this registry value

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Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU

In the left panel, double-click the following: HKEY_LOCAL_MACHINE>SOFTWARE>Policies>Microsoft>Windows>WindowsUpdate>AU

In the right panel, locate and delete the entry:NoAutoUpdate = "1"

Close Registry Editor.

Step 5

Restore these modified registry values

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Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

From: ShowSuperHidden = "0"To: ShowSuperHidden = "1"

To restore registry values this malware/grayware modified:

Open Registry Editor. To do this:

On Windows 2000, XP, and Server 2003: Click Start>Run, type REGEDIT in the text box provided, and then press Enter.

On Windows Vista and 7: Click the Start button, type REGEDIT in the Search input field then press Enter.

In the left panel, double-click the following: HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advanced

In the right panel, locate the registry value: ShowSuperHidden = "0"

Right-click on the value name and choose Modify. Change the value data of this entry to: ShowSuperHidden = "1"

Close Registry Editor.

Step 6

Search and delete AUTORUN.INF files created by WORM_VOBFUS.RU that contain these strings

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{garbage characters}

[autorun]

icon={random}.exe,0

{garbage characters}

open={random}.eXE

{garbage characters}

ACTION=18480

{garbage characters}

UseautopLAY=1

{garbage characters}

To identify and delete AUTORUN.INF files created:

Right-click the Start button then choose Search... or Find..., depending on the version of Windows you are running.

In the Named input box, type:AUTORUN.INF

In the Look in: drop-down list, select a drive, then press Enter.

Select the file, then open using Notepad.

Check if the following lines are present in the file:

{garbage characters}

[autorun]

icon={random}.exe,0

{garbage characters}

open={random}.eXE

{garbage characters}

ACTION=18480

{garbage characters}

UseautopLAY=1

{garbage characters}

If the lines are present, delete the file.

Repeat steps 3 to 6 for the remaining AUTORUN.INF files in other remaining removable drives.

Close Search Results.

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_VOBFUS.RU. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.